Production of artificial filaments, threads, fibres, bands, and the like



United States Patent PRODUCTION OF ARTIFICIAL FILAMENTS, THREADS,FIBRES, BANDS, AND THE LIKE Robert Louis. Wormell, Coventry, England,assignor to Courtaulds Limited, London, England, a British company NoDrawing. Application April 1, 1954, Serial No. 420,439

This invention relates to the production of artificial filaments,threads, fibres, bands and the like, hereinafter referred to generallyas threads, from casein of animal I or vegetable origin, for examplelactic or milk casein, peanutprotein, soya bean protein,.castor beanprotein and similar fibre-formingproteins. This'application is acontinuation-in-part application of my application Serial No. 220,727,filed April 12, 1951, now Patent No. 2,691,568, and contains subjectmatter common to copending application Serial No. 255,912, filedNovember 13, 1951, now Patent No. 2,684,282.

It is known to produce such threads by extruding a solution of theprotein into a'setting medium, for example by extruding a solution ofthe protein in caustic soda into a coagulating bath containing sodiumsulphate and sulphuric acid. It is the usual practice'to subject thefreshlyextruded threads-to theaction offormaldehyde, either alone or inconjunction with an acid or one or more salts, in order to harden thethreads, that is to make them resistant to cold water. The threads arethen usually further treated in order to render them resistant to-hotwater and hot aqueous solutions, sucha process being known as.insolubilising.

The wet properties of artificial protein threads as produced hithertohave not, in general, been entirely satisfactory for some textilepurposes. Thus, the threads usually swell appreciablyin water and indilute alkali solutions such as are used in scouring and milling, sothat fabrics made from protein threads, alone or in admixture with wool,tend to be adversely afliected by standard scouring and millingprocesses. In addition, artificial protein threads which have been dyedhave poor fastness to washing, and standard scouring treatments of dyedprotein threads usually reduce the depth of shade considerably.

German patent specification No. 748,450 describes a process of dyeingand printing natural or artificialprotein fibers or mixtures of suchfibres, wherein the fibres, either during or after the dyeing, aretreated with methanol in the presence of an esterificationcatalyst.

The object of the present. invention is to improve the Wet properties ofprotein threads.

According to the present invention,.in a process for the production ofprotein threads by extruding a solution of a protein into a setting.medium, hardening ,by immersing the freshly-extruded thread so obtainedin a bath containing formaldehyde and one or more of the salts sodiumsulphate, magnesium sulphate and aluminum sulphate until the thread isresistant to the solvent action of cold water, and stretching the threadduring the hardening treatment, the swelling susceptibility of thethread is decreased by the steps of esterifying the thread in a bathcomprising methyl alcohol or ethyl alcohol together with anesterification catalyst such as sulphuric acid at a temperaturebetweenabout 30 C. and about 50 C. for an esterification time of at least /2hourand then subjecting the esterified thread to an insolubilisingtreatment consisting of applying to the esterified thread an aqueous2,775,505 PatentedDec. 25, 1956 solution containing cyanic ions andsubsequently heating the thus-treated thread at an elevated temperature.Suitable temperatures for this heating step are from 60 C. to 70 C. r s

The cyanate insolubilising treatment may be efiected by the processdescribed in British patent specification No. 614,506 according to whichthe protein fibres are immersed in an aqueous bath containing cyanicions, pressed or centrifuged to remove'excess solution, dried, washedand dried again. Itis preferred however to avoid the deposition ofcyanate compounds in the thread during the heating operation as by usingthe process described and claimed in application, Serial No. 255,912according to which the esterified thread is treated with an aqueoussolution containing cyanic ions and excess solution is removed so as tokeep on the esterified thread that amount tained by using amounts ofcyanic ions less than this chemical equivalent. In general, threadshaving satisfactory wet properties for commercial use are obtained byusing from about 2 to about 4 percent of sodium cyanate based on theweight of the esterified thread. These amounts correspond to about 1.3to 2.6 percent of CNO ions, based on the weight of the esterifiedthread. 1 Suitable compounds giving rise to cyanic ions for use inthis'invention are sodium cyanate, potassiumcyanate, ammonium cyanateand calcium cyanate. These salts are preferably applied to the thread insuch quantities as to give 1.3 to 2.6 percent of cyanic ions based onthe weight of the thread.

It is believed that the cyanate compound applied to the esterifiedthread reacts during the drying with the acidic amino acid residueswhich are always present in the thread in excess over the equivalentbasic residues to liberate cyanic acid which then reacts with adjacent=NH groups to give =N.CONH2 groups while any excess is decomposed toammonia. and carbon dioxide thus formed into a fabric and the fabric maythen be treated in an esterification bath followed by a cyanateinsolubilising treatment in accordance with the invention.

The esterification liquid containing sulphuric acid and methyl alcoholorethyl alcohol may also contain water preferably in a proportion notexceeding 30 percent by weight based on the weight of the alcohol.Proportions of water of the order of 20 to 25 percent are particularlysuitable. The use of esterification media containing water is usuallymore economic as compared with the use of similar media which aresubstantially free from water. Baths containing to percent of methylalcohol or ethyl alcohol and 25 to 20 percent of water, with to 240grams per litre of sulphuric acid may be used with good results. Suchesterification is preferably effected at raised temperatures,temperatures of from 35 to 50 C. being particularly suitable. Treatmenttimes are not critical and may conveniently vary from /2 hour to 3hours, depending on the temperature used and the concentration of'theesterification bath.

The addition of a dialkyl sulphate, for example in a proportion of about30 percent by weight based on the weight of the alcohol, assistsin theesterification. The preferred dialkyl sulphate. is diethyl sulphate;

It is also advantageous to pretreat the hardened protein threadsimmediately before the esterification step with the alcohol used in theesterification or, when a mixture of water and alcohol is used in theesterification bath, with an alcohol-water mixture havingthe samecomposition as that present in the esterification bath. Thispretreatment step helps to maintain the composition of theesterification bath substantially constant particularly during prolongedoperations.

The process according to the invention produces protein threads whichare generally white in colour and have reduced water imbibition. Thefastness to washing of threads dyed with a dispersed dye such asAzo-Geranine (Colour Index No. 31) and with chrome dyes. is alsoimproved. The threads are also stable to normal hot acid dyebathscontaining acid dyes, chrome-complex acid dyes, chrome dyes, and also tonormal dyebaths containing direct dyes and solubilised sulphur dyes.

The process according to the invention may include a cutting operationat any convenient stage; the staple fibres produced are particularlysuitable for blending with wool in the manufacture of milled articlessuch as blankets, since the protein fibres are not adversely affected toany appreciable extent by the milling process.

The invention is illustrated by the following examples in which partsand percentages are by weight:

Example 1 A 20 percent solution of milk casein in 1 percent aqueouscaustic soda solution was extruded into a co agulant bath. The resultantthreads after hardening in formaldehyde were stretched 400 percent andwere then hardened further by immersion for 2 hours at a temperature of50 C. in a liquor containing, in each'litre, 250 grams of aluminumsulphate, 250 grams of sodium sulphate and grams of formaldehyde. Thefibres after removal of excess water, washing and pressing were immersedin a methyl alcohol bath at 35 C. Surplus alcohol was. squeezed out andthe fibres were then esterified for one hour at a temperature of 35 C.with parts by weight of a liquor consisting of 6.2 parts by volume ofmethyl alcohol, 2.6 parts by volume of diethyl sulphate and 1 part byvolume of sulphuric acid. The esterified fibres were washed until theyreacted neutral to methyl red and hydroextracted and the moist fibreswere impregnated with a 2 percent aqueous solution of sodium cyanatecontaining 0.1 percent of a soft finish. The fibres were then squeezedto 100 percent expression (i. e. the fibres retained their own weight ofsolution) and were dried at 60 C.

The imbibition of the threads obtained in a 1 percent aqueous sodiumcarbonate solution was 45 percent as compared with 125 percent forcorresponding threads which had been hardened only.

The product obtained was dyed according to standard wool dyeingtechnique in dyebaths containing (a) 0.65 percent of Coomassie Red PG150 (Journal of the Society of Dyers and Colourists, 1939, page 62),

(b) 1 percent Neolan Red BRE (Journal of the Society of Dryers andColourists, 1943, page 123),

(c) 1 percent Alizarine Red AS,

using as a control a thread prepared as described in Example 1 butexcluding only the esterification step. In each case the thread preparedas described in the example was substantially unaffected by the dyeingtreatment whereas the dyed control threads were hard and rather brittle.

Samples of the thread of Example 1 were also compared in the same waywith dyebaths containing;

4 Direct dyes:

0.3 percent Chrysophenine G305 (C. I. 365), 0.5 percent Durazol Blue 2GN200 (Journal of the Society of Dyers and Colourists, 1943, page 124)0.65 percent Chlorazol Dark Green PL (C. I.

583) Solubilised Sulphur dye:

3 percent Thionol Navy Blue RMS.

The dyed threads prepared according to Example 1 were appreciablysuperior to the dyed control threads.

Example 2 Casein fibres which had been initially hardened as describedin Example 1 were soaked in methyl alcohol at a temperature of 40 C. andthe excess alcohol removed by squeezing. The fibres were esterified for1 hour at 35 C. with a liquor consisting of methyl alcohol containing ineach litre grams of sulphuric acid. The esterified fibres were washedfree from acid and hydroextracted. The moist fibres were impregnatedwith a 2 percent solution of sodium cyanate containing 0.1 percent of asoft finish and the excess liquor squeezed out to 150 percent expressionso that the thread retained that amount of cyanate ('3 percent) which isthe chemical equivalent of its acidic amino acid residues. The fibreswere heated at 70 C. for 10 minutes, washed in water and finally dried.

The imbibition of the product was 70 percent.

The dyeing properties of the product were similar to those of theproduct of Example 1.

Example 3 Threads, extruded, hardened and stretched as described inExample 1, were hardened further for 3 hours in a bath at 45 C.containing in each litre 550 grams of aluminum sulphate and 20 grams offormaldehyde. The threads were washed free from excess liquor and werethen esterified by immersion for 45 minutes in methyl alcohol containing350 grams per litre of sulphuric acid, this liquor being at atemperature of 35 C. The threads were washed until they were free fromacid and then immersed for 20 minutes in a 4 percent aqueous sodiumcyanate solution. Excess solution was removed from the threads bysqueezing to 100 percent expression and the threads were dried at 65 C.

What I claim is:

1. In a process for the production of artificial threads from proteinsby extruding a solution of a protein selected from the class consistingof milk casein, peanut protein, soya bean protein, and castor beanprotein into a setting medium, and hardening by immersing the freshlyextruded thread so obtained in a bath containing formaldehyde and ametal salt chosen from the class consisting of sodium sulphate,magnesium sulphate, aluminium sulphate and mixtures of said salts, untilthe thread is resistant to the solvent action of cold water, the methodof decreasing the swelling susceptibility of the thread by the steps ofesterifying the thread in a bath comprising an alcohol chosen from thegroup consisting of methyl alcohol and ethyl alcohol together with anesterification catalyst, at a temperature between about 30 and about 50C. for an esterification time of at least /2 hour and then subjectingthe esterified thread to an insolubilising treatment consisting ofapplying to the esterified thread an aqueous solution containing cyanicions and then heating the thus-treated thread at elevated temperature.

2. A process as claimed in claim 1 wherein the esterification catalystused is sulphuric acid.

3. A process as claimed in claim 1 wherein the esterification bathcontains water in a proportion not exceeding 30 percent by weight basedon the weight of the alcohol.

4. A process as claimed in claim 3 wherein the esterification bathcontains 20 to 25 percent of water based on the weight of the alcohol.

5. A process as claimed in claim 1 and including the step ofpr'etreating the hardened threads immediately before the esterificationstep with the alcohols used in the esterification step.

6. In a process for the production of artificial threads from proteinsby extruding a solution of a protein selected from the class consistingof milk casein, peanut protein, soya bean protein, and castor beanprotein into a setting medium, and hardening by immersing the freshlyextruded thread so obtained in a bath containing formaldehyde and ametal salt chosen from the class consisting of sodium sulphate,magnesium sulphate, aluminium sulphate and mixtures of said salts, untilthe thread is resistant to the solvent action of cold water, the methodof decreasing the swelling susceptibility of the thread by the steps ofesterifying the thread in a bath comprising an alcohol chosen from thegroup consisting of methyl alcohol and ethyl alcohol together with anesterification catalyst, at a temperature between about 30 and about 50C. for an esterification time of at least /2 hour and then subjectingthe esterified thread to an insolubilising treatment consisting oftreating the esterified thread with an aqueous solution containingcyanic ions, and moving excess solution, keeping on the esterifiedthread after said removal step, that amount and substantially only thatamount of cyanic ions which is the chemical equivalent of the acidicamino acid residues in the protein, and drying the thus-treated threadat an elevated temperature.

7. A process as claimed in claim 6 wherein the esterification catalystused is sulphuric acid.

8. A process as claimed in claim 6 wherein the esterification bathcontains Water in a proportion not exceeding 30 percent by weight of thealcohol.

9. A process as claimed in claim 8 wherein the esterification bathcontains 20 to 25 percent of water based on the weight of the alcohol.

10. A process as claimed in claim 6 and including the step ofpretreating the hardened threads immediately before the esterificationstep with the alcohol used in the esterification step.

11. In a process for the production of artificial threads from proteinsby extruding a solution of a protein selected from the class consistingof milk casein, peanut protein, soya bean protein, and castor beanprotein into a setting medium, and hardening by immersing the freshlyextruded thread so obtained in a bath containing formaldehyde and ametal salt chosen from the class consisting of sodium sulphate,magnesium sulphate, aluminium sulphate and mixtures of said salts, untilthe thread is resistant to the solvent action of cold Water, the methodof decreasing the swelling susceptibility of the thread by the steps ofesterifying the thread in a bath comprising an alcohol chosen from thegroup consisting of methyl alcohol and ethyl alcohol together With anesterification catalyst, at a temperature between about 30 and about C.for an esterification time of at least /2 hour and then subjecting theesterified thread to an insolubilising treatment consisting of treatingthe esterified thread with an aqueous solution containing cyanic ionsand removing excess solution, keeping on the esterified thread from 1.3to 2.6 percent of cyanic ions, based on the weight of the esterifiedthread, and drying the thus-treated thread at an elevated temperature.

12. A process as claimed in claim 11 wherein the esterification catalystused is sulphuric acid.

13. A process as claimed in claim 11 wherein the esterification bathcontains water in a proportion not exceeding 30 percent by weight basedon the weight of the alcohol.

14. A process as claimed in claim 13 wherein the esterification bathcontains 20 to 25 percent of water based on the weight of the alcohol.

15. A process as claimed in claim 11 and including the step ofpretreating the hardened threads immediately before the esterificationstep with the alcohol used in the esterification step.

References Cited in the file of this patent UNITED STATES PATENTS2,240,388 Calva Apr. 29, 1941 FOREIGN PATENTS 7 483,731 Great BritainApr. 21, 1938 495,885 Great Britain Nov. 22, 1938 614,506 Great BritainDec. 16, 1948 OTHER REFERENCES Textile Research Journal, April 1949, pp.202-211.

1. IN A PROCESS FOR THE PRODUCTIONOF ARTIFICIAL THREADS FROM PROTEINS BYEXTRUDINGA SOLUTION OF A PROTEIN SELECTED FROM THE CLASS CONSISTING OFMILK CASEIN, PEANUT PROTEIN, SOYA BEAN PROTEIN, AND CASTOR BEAN PROTEININTO A SETTING MEDIUM, AND HARDENING BY IMMERSING THE FRESHLY EXTRUDED,THREAD SO OBTAINED IN A BATH CONTAINING FORMALDEHYDE AND A METAL SALTCHOSEN FROM THE CLASS CONSISTING OF SODIUM SULPHATE, MAGNESIUM SULPHATE,ALUMINIUM SULPHATE AND MIXTURES OF SAID SALTS, UNTIL THE THREAD ISRESISTANT TO THE SOLVENT ACTION OF COLD WATER, THE METHOD OF DECREASINGTHE SWELLING SUSCEPTIBILITY OF THE THREAD BY THE STEPS OF ESTERIFYINGTHE THREAD IN A BATH COMPRISING AN ALCOHOL CHOSEN FROM THE GROUPCONSISTING OF METHYL ALCOHOL AND ETHYL ALCOHOL TOGETHER WITH ANESTERIFICATION CATALST, AT A TEMPERATURE BETWEEN ABOUT 30* AND ABOUT 50*C. FOR AN ESTERIFICATION TIME OF AT LEAST 1/2 HOUR AND THEN SUBJECTINGTHE ESTERIFIED THREAD TO AN INSOLUBILISING TREATMENT CONSISTING OFAPPLYING TO THE ESTERIFIED THREAD AN AQUEOUS SOLUTION CONTAINING CYANICIONS AND THEN HEATING THE THUS-TREATED THREAD AT ELEVATED TEMPERATURE.